• Christoph Lameter's avatar
    Pagecache zeroing: zero_user_segment, zero_user_segments and zero_user · eebd2aa3
    Christoph Lameter authored
    Simplify page cache zeroing of segments of pages through 3 functions
    
    zero_user_segments(page, start1, end1, start2, end2)
    
            Zeros two segments of the page. It takes the position where to
            start and end the zeroing which avoids length calculations and
    	makes code clearer.
    
    zero_user_segment(page, start, end)
    
            Same for a single segment.
    
    zero_user(page, start, length)
    
            Length variant for the case where we know the length.
    
    We remove the zero_user_page macro. Issues:
    
    1. Its a macro. Inline functions are preferable.
    
    2. The KM_USER0 macro is only defined for HIGHMEM.
    
       Having to treat this special case everywhere makes the
       code needlessly complex. The parameter for zeroing is always
       KM_USER0 except in one single case that we open code.
    
    Avoiding KM_USER0 makes a lot of code not having to be dealing
    with the special casing for HIGHMEM anymore. Dealing with
    kmap is only necessary for HIGHMEM configurations. In those
    configurations we use KM_USER0 like we do for a series of other
    functions defined in highmem.h.
    
    Since KM_USER0 is depends on HIGHMEM the existing zero_user_page
    function could not be a macro. zero_user_* functions introduced
    here can be be inline because that constant is not used when these
    functions are called.
    
    Also extract the flushing of the caches to be outside of the kmap.
    
    [akpm@linux-foundation.org: fix nfs and ntfs build]
    [akpm@linux-foundation.org: fix ntfs build some more]
    Signed-off-by: default avatarChristoph Lameter <clameter@sgi.com>
    Cc: Steven French <sfrench@us.ibm.com>
    Cc: Michael Halcrow <mhalcrow@us.ibm.com>
    Cc: <linux-ext4@vger.kernel.org>
    Cc: Steven Whitehouse <swhiteho@redhat.com>
    Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
    Cc: "J. Bruce Fields" <bfields@fieldses.org>
    Cc: Anton Altaparmakov <aia21@cantab.net>
    Cc: Mark Fasheh <mark.fasheh@oracle.com>
    Cc: David Chinner <dgc@sgi.com>
    Cc: Michael Halcrow <mhalcrow@us.ibm.com>
    Cc: Steven French <sfrench@us.ibm.com>
    Cc: Steven Whitehouse <swhiteho@redhat.com>
    Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    eebd2aa3
direct-io.c 34.2 KB